docs: def Erdim_Akgiray_Demir(dp, voidage, vs, rho, mu, L=1):
      r'''Calculates pressure drop across a packed bed of spheres using a
      correlation developed in [1]_, claiming to be the best model to date.
  
      .. math::
          f_v = 160 + 2.81Re_{Erg}^{0.904}
  
      .. math::
          f_v = \frac{\Delta P d_p^2}{\mu v_s L}\frac{\epsilon^3}{(1-\epsilon)^2}
  
      .. math::
          Re_{Erg} = \frac{\rho v_s  d_p}{\mu(1-\epsilon)}
  
      Parameters
      ----------
      dp : float
          Particle diameter of spheres [m]
      voidage : float
          Void fraction of bed packing [-]
      vs : float
          Superficial velocity of the fluid (volumetric flow rate/cross-sectional 
          area)[m/s]
      rho : float
          Density of the fluid [kg/m^3]
      mu : float
          Viscosity of the fluid, [Pa*s]
      L : float, optional
          Length the fluid flows in the packed bed [m]
  
      Returns
      -------
      dP : float
          Pressure drop across the bed [Pa]
  
      Notes
      -----
      Developed with data in the range of:
  
      .. math::
          2 < Re_{Erg} <3582\\
          4 < d_t/d_p < 34.1\\
          0.377 < \epsilon <0.470
  
      Examples
      --------
      >>> Erdim_Akgiray_Demir(dp=8E-4, voidage=0.4, vs=1E-3, rho=1E3, mu=1E-3)
      1438.2826958844414
  
      References
      ----------
      .. [1] Erdim, Esra, Ömer Akgiray, and İbrahim Demir. "A Revisit of Pressure
         Drop-Flow Rate Correlations for Packed Beds of Spheres." Powder
         Technology 283 (October 2015): 488-504. doi:10.1016/j.powtec.2015.06.017.
      '''
      Rem = dp*rho*vs/mu/(1-voidage)
      fv = 160 + 2.81*Rem**0.904
      return fv*(mu*vs*L/dp**2)*(1-voidage)**2/voidage**3